A PurpleAir air quality monitoring sensor was installed at multiple sites within the CT DEEP monitoring network to evaluate the sensors performance tracking PM_2.5 data against a reference. PurpleAir data was corrected using the extended U.S-wide correction equation developed by the EPA to reduce bias in sensor data (more information found here: AirNow). Hourly data from 2023 was then compared to a T640X reference monitor located at the same location. The full dataset used can be downloaded here Download CSV.

Site Locations

Sensor Details

PurpleAir Specifications

Possible Configuration	Evaluated Configuration	Cost	Data Access	Power Supply	Considerations	Reference Monitor Compared
PM2.5, Temperature, Relative Humidity, Pressure	PM2.5	Sensor: $229-$299 Outdoor Power Supply: $40	Micro SD card, WiFi connectivity, API download and live public online map	Potted 5V USB outdoor power supply 12 ft mains plug	-Affected by saltwater (issues with coastal use) -Life Expectancy ~2 years -Some parts replaceable, model specific	PM2.5: Teledyne API T640X

Setup

Timeseries Comparison

PurpleAir hourly data for PM_2.5 were compared by quarter to reference values from a T640X analyzer (Q1: January-March, Q2: April-June, Q3: July-September, Q4: October-December).

Bridgeport

Quarter 1

Quarter 2

Quarter 3

Quarter 4

Cornwall

Quarter 1

Quarter 2

Quarter 3

Quater 4

Danbury

Quarter 1

Quarter 2

Quarter 3

Quarter 4

East Hartford

Quarter 1

Quarter 2

Quarter 3

Quarter 4

Groton

Quarter 1

Quarter 2

Quarter 3

Quarter 4

Hartford

Quarter 1

Quarter 2

Quarter 3

Quarter 4

New Haven

Quarter 1

Quarter 2

Quarter 3

Quarter 4

Waterbury

Quarter 1

Quarter 2

Quarter 3

Quarter 4

Correlation Comparison

PurpleAir and Reference Correlation

Bridgeport

Cornwall

Danbury

East Hartford

Groton

Hartford

New Haven

Waterbury

Results Summary